Finish notifirc integration with newer notifirc version via stdin

dotfiles/imapfilter/common/functions.lua

     return mbox.FILTER_QUEUE:is_newer(84)
 end
 
-function _notifirc1(structure)
+function _notifirc1(subj, from, body)
     --notify about message using (pre-configured) notifirc
-    os.execute('notifirc "A funny message arrived!"; notifirc "too bad we are SO WEAK"')
+    local fd = assert(io.popen('notifirc -f - "message preview:"', "w"))
+    local fmt = "> Subject: %s\n> From: %s\n> Body: %s"
+    fd:write(fmt:format(subj, from, body))
+    fd:close()
 end
 
 function notifirc_all(seq)
     for _, mesg in ipairs(seq) do
         mbox, uid = table.unpack(mesg)
-        structure = mbox[uid]:fetch_structure()
-        _notifirc1(structure)
+        subj = mbox[uid]:fetch_field('Subject')
+        from = mbox[uid]:fetch_field('From')
+        body = mbox[uid]:fetch_body()
+        _notifirc1(subj, from, body)
     end
 end